But Moira doesn't remember anything about Charles or the X-Men or at least very little apart from sunshine and a kiss.

How's she going to figure into the plot of DoFP?

that was a wrong decision, in my opinion.

In any case, I think she still has to be present on this sequel, even if the role is small. She is Charle's only love interest in this franchise, so the studio should keep her in to let the audience gets more familiar with her, and to develop her a bit more on the third movie.

Its about time the x-men franchise started showing love interest for the main characters. X-men movies shouldnt be just about heroes vs villains. So this love interest in particular should stay during the series.